By the numbers: How much faster are Windows 8.1 apps with new code?

Yesterday during a Build session, Microsoft software engineer Polita Paulus held a session on what it means for developers to upgrade their apps for Windows 8.1. While current Windows 8 apps will of course run just fine on 8.1, developers interested in taking advantage of the new code base will need to recompile their app and add or modify a few lines of code.

Like all OS updates, those of you who are straight up consumers just want to know, what does it mean for me? We know already that in 8.1 the “snap view” is basically gone in the sense that predefined sizes (1/3 or 2/3 of the display) are no longer required. That means you can drag and resize multiple “snapped” windows to whatever size you want.

But what about speed changes? Of course an OS update should bring optimizations to the codebase, allowing apps to load quicker and indeed on 81, that is the case.

In a slide (and subsequent demo) we’re told that apps recompiled for 8.1 have quite a few advantages to them for speed:

5-30% increase in Startup time (in an app with ListView e.g. Mail)

2x List Planning

10-20% lower memory usage in XAML

15-35% faster: Editing in a WinJS ListView

In real world terms, we saw what this meant in the much used Mail app for Windows 8. The app started faster and when scrolling fast there were no fill-boxes (i.e. the grey background) resulting in a visually much improved system.

Developers won’t have to do much either to take advantage of 8.1, as in most instances a simple recompile is all that is needed. However, devs may need to spend a little time tweaking how their app looks when snapped at various sizes, including what its ideal would be.

Regardless, in the end yes, your apps will start faster, be smoother at scrolling and use less memory, just as you would expect.

I have the Surface RT as well and have found the responiveness to be greatly improved. I'm assuming the skydrive app has been updated to the 8.1 code, cause it used to be a dog, and now it's extremely fast.
Give the preview a shot! Unless ofcourse you use your Surface for mission critical stuff.

I didn't made a recovery but probably good idea in hindsight:-). I think it's little bit faster but more important you can now finally have 2 apps side by side (min. size is 1/3 though). Also links are now opened split screen.
Also like the change to use same background in start menu so switching from desktop to start so transition is much smoother.

Sorry to say, but just because you don't experience any sluggishness doesn't mean nobody else hasn't. I have a Surface RT and a Windows 8 laptop, and I can see the difference in opening apps, for instance, is night and day. Plus, it is a well-documented fact that the Tegra3 is an underpowered processor for WinRT.

I've never suggested people aren't experiencing sluggishness, I'm just curious about what exactly is sluggish. I don't think you should expect a low powered tablet to work like a high powered desktop. Comparing to an iPad2 or 3 is perfectly appropriate since we are talking about similar hardware.

Your comment "What crappy sluggishness" seemed to imply that the point I brought up was totally unheard of (esp since you rephrased *crappy processor's* sluggishness to crappy sluggishness). sorry for the misunderstanding.
As far as what exactly is sluggish, its basic things, like opening apps like Mail. They just take quite a bit of time just to open (not sync, just open). And when I open the news app, the front page displays the old outdated news headline for a fair amount of time and finally the app refreshes that page with the latest headline. The photos app, please dont even get me started with that one. There are so many syncing issues that I've given up using the Photos app and just go to desktop mode and browse my photos from the file manager.

of cuorse everybody's aren't, what gave you the impression I implied that? Your's may be running fine. I find mine not up to par. Is that outside the realm of possibility? And the term fine is subjective. What may seem fine to one may not be fine by somebody else's standard.

The question is...is RT faster before or after the 8.1 update and the answer for most it seems is that it is indeed more responsive. Comparing it to your Windows 8 install is makes no sense. The most noticeable improvement I've seen so far is that Xbox Live games long in faster than prior to the update.

I respectfully disagree. To me it makes sense. Intel maybe a powerful processor, but its powering a heavier OS. ARM, while less powerful, is powering a lighter OS. The beauty of engineering lies in delivering the same top notch / fluid experience across the range of devices - regardless of the OS and processor.
Anyways, I'm installing 8.1 preview right now, hoping to see some performance improvements.

I have found that after all the indexing and various other tasks that take place after the upgrade that my Surface RT is much much more responsive than it was under Win 8. I am really liking the changes in 8.1 so far.

Oops. Guess my comment's winky face didn't make my hidden intents clear enough. I completely understand that. I was just quipping that it would be nice if all apps could be recompiled sooner than later(i.e. before Microsoft patches more bugs) in order to take advantage of the notable performance and other accompanying improvements doing so would bring along.

keep an eye on your disk performance. we've had to reset quite a few RT devices at work because disk IO was off the charts. Always running 100% with >2000ms response times. A factory rest resolved the issue everytime.

Definately still bugs to work out, as should be expected with beta/preview releases. Two of my 3 mail accounts wont connect and I've had a few app crashes. If you cant live with that sort of thing, wait until the final, real release of 8.1.

Idk what the sluggishness is my surface is an animal it might hang up after switching between 5 or 6 apps especially when two running at a time but what tablet have u seen comes close to that type of power

This is completly false. I have yet to encounter a bit of sluggishness on my Surface RT, Lenovo W530 or HP 6005 Pro desktop. All are now running 8.1 If you don't know what you are doing you should stay away and leave previews for those of us in IT that know what we are talking about.

How does the store/developers cope with API differences/app releases? Can we release the app targetted to 2 platforms (8/8.1) or the second we push out a 8.1 app do older users no longer get to see it? Or has Microsoft kind of forgotten about this and assume that everyone will definitely upgrade?

Looking forward to the improvements. But I am going to hold off for now, becuase my Surface Pro is humming along. As are my Acer netbook running AMD's equivalent to a 2 1/2-year-old Atom (though not nearly as speedy as an i5, of course) and my wife and daugter's 3 year-old i3-based notebooks.